Accuracy of visible retinal emboli for the detection of cardioembolic lesions requiring anticoagulation or cardiac surgery

Aim - To determine the accuracy of visible retinal emboli as a diagnostic 'test' for the likelihood of receiving anticoagulation or cardiac surgery based on the results of transthoracic echocardiography, in the setting of acute retinal arterial occlusion. Methods - A multicentre retrospective diagnostic study at Kingston Eye Centre, Queen's University, Kingston, Ontario; Wills Eye Hospital, Philadelphia; Ottawa Eye Institute, Ottawa, Ontario; and the Halifax Infirmary, Halifax, Nova Scotia of 104 patients with both embolic and non-embolic acute retinal arterial obstruction who underwent transthoracic echocardiography was performed, to determine the accuracy of visible retinal emboli as a diagnostic 'test' for anticoagulation or cardiac surgery. Anticoagulation or surgical intervention on the basis of abnormalities was detected solely through the technology of transthoracic echocardiography. Results - 41 patients had visible retinal emboli (calcific, cholesterol, or fibrin). The remaining 63 had no evidence of embolic disease. The sensitivity of emboli for the likelihood of a patient receiving anticoagulation or cardiac surgery was 50%. The specificity, positive predictive value, and negative predictive value were 62%, 15%, and 90%, respectively. The likelihood ratio (LR = 1.31) obtained given the presence of a visible retinal embolus was neither clinically nor statistically significant (LR + ve = 1.31; 95% CI (0.91, 3.16)). This likelihood ratio, when applied to a patient with a pretest probability of 50%, results in a post-test probability of 56.7%. Conclusions - These results demonstrate that the presence of a visible retinal embolus should not be the sole determinant of whether to order transthoracic echocardiography, as the likelihood ratio for a patient receiving anticoagulation or cardiac surgery, given the presence of a visible retinal embolus was only 1.31.